Coronary artery bypass surgery has been demonstrated to relieve angina and improve the quality of life in patients with multivessel coronary artery disease. Percutaneous transluminal coronary angioplasty (PTCA) is a new nonsurgical revascularization technique that is increasingly being used for the treatment of patients with multivessel coronary disease. While efficacy of PTCA in the treatment of patients with single vessel disease is generally accepted, this is not the case for patients with multivessel disease. Therefore, the primary aim of this trial will be to test the hypothesis that PTCA is as effective as CABG in the treatment of patients with multivessel disease and severe symptoms as shown by an equivalent relief of angina without increased risk of death or nonfatal MI over 5 years. A randomizable group of patients will be derived from a registry and will satisfy entry criteria to include: Less than 76 years of age, stable angina CHC III-IV or unstable angina with multivessel CAD felt to be adequately treatable by either CABG or PTCA. The patients should have no prior revascularization procedure and no significant noncoronary or noncardiac disease. Patients consenting to randomization will be followed at 6 month intervals for 5 years. In patients capable of exercise, a thallium exercise test will be obtained before, and at 1 month and 1, 3, and 5 years after revascularization. A repeat cardiac catheterization will be obtained on all patients at 5 years. Angina relief assessed by a detailed questionnaire, physician interview, and anginal log will be compared between groups. Mortality and morbidity will be closely monitored. If PTCA is shown to be as effective as CABG in the relief of angina without any increased risk of death or nonfatal MI, this finding would have a major impact on the management of patients with coronary artery disease.